Mortgage Banking Activities Mortgage Banking Activities, Loans Serviced for Others (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans Serviced For Others, Current	$ 12,000,106
Loans Serviced For Others, 30 To 59 Days Past Due	167,148
Loans Serviced For Others, 60 To 89 Days Past Due	33,846
Loans Serviced For Others, Greater Than 90 Days or More Past Due	71,591
Loans Serviced For Others	12,272,691
Federal Home Loan Mortgage Corporation Certificates and Obligations (FHLMC) [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans Serviced For Others, Current	4,583,387
Loans Serviced For Others, 30 To 59 Days Past Due	33,374
Loans Serviced For Others, 60 To 89 Days Past Due	8,253
Loans Serviced For Others, Greater Than 90 Days or More Past Due	37,211
Loans Serviced For Others	4,662,225
Federal National Mortgage Association Certificates and Obligations (FNMA) [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans Serviced For Others, Current	2,959,423
Loans Serviced For Others, 30 To 59 Days Past Due	19,375
Loans Serviced For Others, 60 To 89 Days Past Due	4,064
Loans Serviced For Others, Greater Than 90 Days or More Past Due	17,945
Loans Serviced For Others	3,000,807
Government National Mortgage Association Certificates and Obligations (GNMA) [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans Serviced For Others, Current	4,219,579
Loans Serviced For Others, 30 To 59 Days Past Due	112,968
Loans Serviced For Others, 60 To 89 Days Past Due	20,962
Loans Serviced For Others, Greater Than 90 Days or More Past Due	11,391
Loans Serviced For Others	4,364,900
Other Investor Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans Serviced For Others, Current	237,717
Loans Serviced For Others, 30 To 59 Days Past Due	1,431
Loans Serviced For Others, 60 To 89 Days Past Due	567
Loans Serviced For Others, Greater Than 90 Days or More Past Due	5,044
Loans Serviced For Others	$ 244,759